Matrix metalloproteinase (MMP) 2, MMP7 and MMP9 are important members of the MMP family. Four polymorphisms in the promoter region of these MMPs, which are MMP2 -1306 C>T, MMP2 -735 C>T, MMP7 -181 A>G and MMP9 -1562 C>T, have been reported to be functional and may contribute to genetic susceptibility to cancers. However, the associations between these polymorphisms and cancer risk remain inconclusive due to conflicting results from different case-control studies. To better evaluate the role of these polymorphisms in cancer development, we conducted a meta-analysis that included 51 studies, with more than 40,000 subjects. The results showed that under dominant genetic model, MMP2 -1306 T was associated with lower susceptibility to lung cancer [odds ratio (OR) = 0.50, 95% confidence interval (CI) 0.43-0.59, P(heterogeneity) = 0.147, I(2) = 44.1%], head and neck cancer (OR = 0.53, 95% CI 0.41-0.69, P(heterogeneity) = 0.974, I(2) = 0.0%) and oesophageal cancer (OR = 0.67, 95% CI 0.55-0.80, P(heterogeneity) = 0.593, I(2) = 0.0%); MMP2-735T was associated with lower risk in lung cancer (OR = 0.65, 95%CI 0.53-0.79, P(heterogeneity) = 0.42, I(2) = 0.0%) and oesophageal cancer (OR = 0.84, 95% CI 0.70-0.99, P(heterogeneity) = 0.206, I(2) = 37.4%); MMP7 -181 AG and GG genotype carriers had an increased gastric cancer risk (OR = 1.90, 95% CI 1.43-2.51, P(heterogeneity) = 0.992, I(2) = 0.0%) and MMP9 -1562 C>T was not associated with cancer risk in the whole group analysis (OR = 0.99, 95% CI 0.91-1.08, P(heterogeneity) = 0.419, I(2) = 3.0%) and subgroup analyses. In all, our meta-analysis suggests that MMP2 -1306 C>T, MMP2 -735 C>T and MMP7 -181 A>G may play allele-specific roles in cancer development, while MMP9 -1562 C>T may not be a major risk factor for most cancer types. Large case-control studies should be performed to clarify the possible roles of these four polymorphisms in different kinds of cancer in more detail.